Former Democratic US presidential candidate John Edwards is set to endorse Barack Obama's White House bid.
The 2004 vice presidential nominee was heavily courted by both Mr Obama and rival Hillary Clinton in the past few months.
He will make the endorsement at a Grand Rapids rally.
The announcement would underline Ms Clinton's failure to translate her landslide win in West Virginia primary into a meaningful dent on Mr Obama's lead in the numbers of Democratic delegates.
Mr Edwards could now release his 19 pledged delegates to Mr Obama, and help him reach out to the white, working-class voters who have flocked to Ms Clinton's flag and who will play a key role in November's general election.
The former first lady routed Mr Obama by 67% to 26% in West Virginia, and was the runaway leader with white and lower-income voters.
In her victory speech, Senator Clinton said she was 'more determined than ever' to carry on her campaign.
Senator Clinton, who faces huge odds in the closing stages of this race, repeated her call for the results of disputed primaries in Florida and Michigan to be counted.
Speaking before a cheering crowd of supporters in Charleston, West Virginia, Senator Clinton described her victory in the state as 'overwhelming'.
She said she was continuing in the race because she believes she is the strongest candidate in the party's presidential nomination contest.
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